TY - JOUR

T1 - Arabidopsis J-protein J20 delivers the first enzyme of the plastidial isoprenoid pathway to protein quality control

AU - Pulido, Pablo

AU - Toledo-Ortiz, Gabriela

AU - Phillips, Michael A.

AU - Wright, Louwrance P.

AU - Rodríguez-Concepción, Manuel

PY - 2013/10

Y1 - 2013/10

N2 - Plastids provide plants with metabolic pathways that are unique among eukaryotes, including the methylerythritol 4-phosphate pathway for the production of isoprenoids essential for photosynthesis and plant growth. Here, we show that the first enzyme of the pathway, deoxyxylulose 5-phosphate synthase (DXS), interacts with the J-protein J20 in Arabidopsis thaliana. J-proteins typically act as adaptors that provide substrate specificity to heat shock protein 70 (Hsp70), a molecular chaperone. Immunoprecipitation experiments showed that J20 and DXS are found together in vivo and confirmed the presence of Hsp70 chaperones in DXS complexes. Mutants defective in J20 activity accumulated significantly increased levels of DXS protein (but no transcripts) and displayed reduced levels of DXS enzyme activity, indicating that loss of J20 function causes posttranscriptional accumulation of DXS in an inactive form. Furthermore, J20 promotes degradation of DXS following a heat shock. Together, our data indicate that J20 might identify unfolded or misfolded (damaged) forms of DXS and target them to the Hsp70 system for proper folding under normal conditions or degradation upon stress.

AB - Plastids provide plants with metabolic pathways that are unique among eukaryotes, including the methylerythritol 4-phosphate pathway for the production of isoprenoids essential for photosynthesis and plant growth. Here, we show that the first enzyme of the pathway, deoxyxylulose 5-phosphate synthase (DXS), interacts with the J-protein J20 in Arabidopsis thaliana. J-proteins typically act as adaptors that provide substrate specificity to heat shock protein 70 (Hsp70), a molecular chaperone. Immunoprecipitation experiments showed that J20 and DXS are found together in vivo and confirmed the presence of Hsp70 chaperones in DXS complexes. Mutants defective in J20 activity accumulated significantly increased levels of DXS protein (but no transcripts) and displayed reduced levels of DXS enzyme activity, indicating that loss of J20 function causes posttranscriptional accumulation of DXS in an inactive form. Furthermore, J20 promotes degradation of DXS following a heat shock. Together, our data indicate that J20 might identify unfolded or misfolded (damaged) forms of DXS and target them to the Hsp70 system for proper folding under normal conditions or degradation upon stress.

KW - Arabidopsis

KW - Arabidopsis Proteins

KW - Chloroplasts

KW - Gene Expression Regulation, Plant

KW - HSP70 Heat-Shock Proteins

KW - Metabolic Networks and Pathways

KW - Plants, Genetically Modified

KW - Protein Interaction Mapping

KW - Terpenes

KW - Transferases

U2 - 10.1105/tpc.113.113001

DO - 10.1105/tpc.113.113001

M3 - Journal article

C2 - 24104567

VL - 25

SP - 4183

EP - 4194

JO - Plant Cell

JF - Plant Cell

SN - 1040-4651

IS - 10

ER -